js/src/yarr/OSAllocatorPosix.cpp@6474c204b198 (annotated)
js/src/yarr/OSAllocatorPosix.cpp
Wed, 31 Dec 2014 06:09:35 +0100
- author
- Michael Schloh von Bennewitz <michael@schloh.com>
- date
- Wed, 31 Dec 2014 06:09:35 +0100
- changeset 0
- 6474c204b198
- permissions
- -rw-r--r--
Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.
| michael@0 | 1 | /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- |
| michael@0 | 2 | * vim: set ts=8 sts=4 et sw=4 tw=99: |
| michael@0 | 3 | * |
| michael@0 | 4 | * ***** BEGIN LICENSE BLOCK ***** |
| michael@0 | 5 | * Copyright (C) 2010 Apple Inc. All rights reserved. |
| michael@0 | 6 | * |
| michael@0 | 7 | * Redistribution and use in source and binary forms, with or without |
| michael@0 | 8 | * modification, are permitted provided that the following conditions |
| michael@0 | 9 | * are met: |
| michael@0 | 10 | * 1. Redistributions of source code must retain the above copyright |
| michael@0 | 11 | * notice, this list of conditions and the following disclaimer. |
| michael@0 | 12 | * 2. Redistributions in binary form must reproduce the above copyright |
| michael@0 | 13 | * notice, this list of conditions and the following disclaimer in the |
| michael@0 | 14 | * documentation and/or other materials provided with the distribution. |
| michael@0 | 15 | * |
| michael@0 | 16 | * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS'' |
| michael@0 | 17 | * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, |
| michael@0 | 18 | * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
| michael@0 | 19 | * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS |
| michael@0 | 20 | * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
| michael@0 | 21 | * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
| michael@0 | 22 | * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
| michael@0 | 23 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
| michael@0 | 24 | * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
| michael@0 | 25 | * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF |
| michael@0 | 26 | * THE POSSIBILITY OF SUCH DAMAGE. |
| michael@0 | 27 | * |
| michael@0 | 28 | * ***** END LICENSE BLOCK ***** */ |
| michael@0 | 29 | |
| michael@0 | 30 | #include "assembler/wtf/Platform.h" |
| michael@0 | 31 | |
| michael@0 | 32 | #if WTF_OS_UNIX && !WTF_OS_SYMBIAN |
| michael@0 | 33 | |
| michael@0 | 34 | #include "yarr/OSAllocator.h" |
| michael@0 | 35 | |
| michael@0 | 36 | #include <errno.h> |
| michael@0 | 37 | #include <sys/mman.h> |
| michael@0 | 38 | #include "assembler/wtf/Assertions.h" |
| michael@0 | 39 | |
| michael@0 | 40 | namespace WTF { |
| michael@0 | 41 | |
| michael@0 | 42 | void* OSAllocator::reserveUncommitted(size_t bytes, Usage usage, bool writable, bool executable) |
| michael@0 | 43 | { |
| michael@0 | 44 | void* result = reserveAndCommit(bytes, usage, writable, executable); |
| michael@0 | 45 | #if HAVE_MADV_FREE_REUSE |
| michael@0 | 46 | // To support the "reserve then commit" model, we have to initially decommit. |
| michael@0 | 47 | while (madvise(result, bytes, MADV_FREE_REUSABLE) == -1 && errno == EAGAIN) { } |
| michael@0 | 48 | #endif |
| michael@0 | 49 | return result; |
| michael@0 | 50 | } |
| michael@0 | 51 | |
| michael@0 | 52 | void* OSAllocator::reserveAndCommit(size_t bytes, Usage usage, bool writable, bool executable) |
| michael@0 | 53 | { |
| michael@0 | 54 | // All POSIX reservations start out logically committed. |
| michael@0 | 55 | int protection = PROT_READ; |
| michael@0 | 56 | if (writable) |
| michael@0 | 57 | protection |= PROT_WRITE; |
| michael@0 | 58 | if (executable) |
| michael@0 | 59 | protection |= PROT_EXEC; |
| michael@0 | 60 | |
| michael@0 | 61 | int flags = MAP_PRIVATE | MAP_ANON; |
| michael@0 | 62 | |
| michael@0 | 63 | #if WTF_OS_DARWIN && !defined(BUILDING_ON_TIGER) |
| michael@0 | 64 | int fd = usage; |
| michael@0 | 65 | #else |
| michael@0 | 66 | int fd = -1; |
| michael@0 | 67 | #endif |
| michael@0 | 68 | |
| michael@0 | 69 | void* result = 0; |
| michael@0 | 70 | #if (WTF_OS_DARWIN && WTF_CPU_X86_64) |
| michael@0 | 71 | if (executable) { |
| michael@0 | 72 | // Cook up an address to allocate at, using the following recipe: |
| michael@0 | 73 | // 17 bits of zero, stay in userspace kids. |
| michael@0 | 74 | // 26 bits of randomness for ASLR. |
| michael@0 | 75 | // 21 bits of zero, at least stay aligned within one level of the pagetables. |
| michael@0 | 76 | // |
| michael@0 | 77 | // But! - as a temporary workaround for some plugin problems (rdar://problem/6812854), |
| michael@0 | 78 | // for now instead of 2^26 bits of ASLR lets stick with 25 bits of randomization plus |
| michael@0 | 79 | // 2^24, which should put up somewhere in the middle of userspace (in the address range |
| michael@0 | 80 | // 0x200000000000 .. 0x5fffffffffff). |
| michael@0 | 81 | intptr_t randomLocation = 0; |
| michael@0 | 82 | randomLocation = arc4random() & ((1 << 25) - 1); |
| michael@0 | 83 | randomLocation += (1 << 24); |
| michael@0 | 84 | randomLocation <<= 21; |
| michael@0 | 85 | result = reinterpret_cast<void*>(randomLocation); |
| michael@0 | 86 | } |
| michael@0 | 87 | #endif |
| michael@0 | 88 | |
| michael@0 | 89 | result = mmap(result, bytes, protection, flags, fd, 0); |
| michael@0 | 90 | if (result == MAP_FAILED) |
| michael@0 | 91 | CRASH(); |
| michael@0 | 92 | return result; |
| michael@0 | 93 | } |
| michael@0 | 94 | |
| michael@0 | 95 | void OSAllocator::commit(void* address, size_t bytes, bool, bool) |
| michael@0 | 96 | { |
| michael@0 | 97 | #if HAVE_MADV_FREE_REUSE |
| michael@0 | 98 | while (madvise(address, bytes, MADV_FREE_REUSE) == -1 && errno == EAGAIN) { } |
| michael@0 | 99 | #else |
| michael@0 | 100 | // Non-MADV_FREE_REUSE reservations automatically commit on demand. |
| michael@0 | 101 | UNUSED_PARAM(address); |
| michael@0 | 102 | UNUSED_PARAM(bytes); |
| michael@0 | 103 | #endif |
| michael@0 | 104 | } |
| michael@0 | 105 | |
| michael@0 | 106 | void OSAllocator::decommit(void* address, size_t bytes) |
| michael@0 | 107 | { |
| michael@0 | 108 | #if HAVE_MADV_FREE_REUSE |
| michael@0 | 109 | while (madvise(address, bytes, MADV_FREE_REUSABLE) == -1 && errno == EAGAIN) { } |
| michael@0 | 110 | #elif HAVE_MADV_FREE |
| michael@0 | 111 | while (madvise(address, bytes, MADV_FREE) == -1 && errno == EAGAIN) { } |
| michael@0 | 112 | #elif HAVE_MADV_DONTNEED |
| michael@0 | 113 | while (madvise(address, bytes, MADV_DONTNEED) == -1 && errno == EAGAIN) { } |
| michael@0 | 114 | #else |
| michael@0 | 115 | UNUSED_PARAM(address); |
| michael@0 | 116 | UNUSED_PARAM(bytes); |
| michael@0 | 117 | #endif |
| michael@0 | 118 | } |
| michael@0 | 119 | |
| michael@0 | 120 | void OSAllocator::releaseDecommitted(void* address, size_t bytes) |
| michael@0 | 121 | { |
| michael@0 | 122 | int result = munmap(address, bytes); |
| michael@0 | 123 | if (result == -1) |
| michael@0 | 124 | CRASH(); |
| michael@0 | 125 | } |
| michael@0 | 126 | |
| michael@0 | 127 | } // namespace WTF |
| michael@0 | 128 | |
| michael@0 | 129 | #endif |
